The present invention relates to fluid flow control devices. The invention is particularly useful for automatically regulating the outlet pressure of a water supply line, and is therefore described herein with respect to that application.
A large number of water pressure regulators are known and in use. The present invention provides fluid flow control devices, and particularly water pressure regulators, which, when compared to most or all of the known devices, are sensitive and immediately responsive to small changes in pressure, simple in construction, and inexpensive to produce. SUMMARY OF THE INVENTION
According to the present invention, there is provided a fluid flow control device comprising a housing having an inlet and an outlet joined by a passageway including a cylindrical chamber and an inwardly extending annular shoulder at the inlet end of the chamber. A sleeve, formed with a plurality of outer axial ribs engageable with the inwardly extending annular shoulder for guiding the movement of the sleeve, is axially movable within the cylindrical chamber to enlarge or restrict the passageway in order to control the fluid flow therethrough from the inlet to the outlet. The device further includes a cylinder fixed to the housing, and a piston movable within the cylinder and connected to the sleeve to move same for controlling the fluid flow through the passageway. A spring between the cylinder and piston biases the piston outwardly of the cylinder in the direction moving the sleeve to enlarge the passageway. A first annular sealing element is fixed to the cylinder in position to be engaged by one end face of the sleeve when the sleeve is moved to one extreme position, and a second annular sealing element is fixed on the outer surface of the opposite end of the sleeve to engage the inwardly extending annular shoulder of the housing when the sleeve is in this extreme position. This closing of the passageway by both ends of the sleeve when moved to this extreme position causes the control device to regulate the outlet pressure even when the water flow downstream is terminated, thereby enabling the downstream installation to be designed for the low, regulated outlet pressure.
A number of embodiments are described below. In one embodiment, the cylinder is fixed off-line of the line between the inlet and the passageway, the sleeve being movable toward and away from the cylinder to restrict and enlarge, respectively, the passageway.
In other embodiments, the cylinder is fixed on-line within the passageway by means of spider-arms supporting same within the passageway spaced from the walls thereof.
According to a further embodiment, the housing includes a second movable sleeve enclosing the first sleeve, and actuating means for moving the second sleeve to close the passageway by bringing one end of the second sleeve into sealing engagement with the cylinder and the opposite end of the second sleeve into sealing engagement with the inner face of the passageway.
Further features and advantages of the invention will be apparent from the description below.